HOUSTON -- On the last day of the LNG 17 conference, executives
from companies involved in floating liquefied natural gas
(FLNG) projects discussed the benefits, challenges, and
technologies involved in the design of FLNG vessels. The
ballroom was packed with attendees eager to hear more on the
development of this new LNG production solution. The following
passages offer highlights from LNG 17s morning panel
session on FLNG.

Shells Prelude project
and lean FLNG. The first speaker, General Manager of
Shell LNG Development for Shell Global Solutions International,
Barend Pek, discussed Shells Prelude project in
Australiathe first FLNG vessel scheduled to come into
operationas well as a new lean FLNG design
Shell has developed for higher-capacity FLNG.

An FLNG project with a Prelude-like design
is anticipated to produce 5.3 million tons per year (MMtpy) to
5.5 MMtpy of LNG, said Mr. Pek. However, Shells lean FLNG
design will bring down the unit technical costs of FLNG
projects by expanding liquefaction capacity, and it is a prime
solution for lean gas fields. The technology involves simplified LNG
extraction and the removal of the LPG extraction component.
Lean FLNG also uses two trains instead of one, and a
refrigerant import instead of refrigerant from its own feed.
Aeroderivative gas turbines are incorporated into the lean FLNG
design.

Mr. Pek noted that a side-by-side offloading system is a
major improvement for FLNG projects, as it lowers stresses on
the manifolds for LNG carriers and ensures successful
offloading in harsh environmental conditions. Shell
plans to continue development work to cater to larger and
leaner gas fields, Mr. Pek said. Prelude is presently being
assembled at the Samsung Heavy Industries yard.

During the Q&A session following Mr. Peks
presentation, a conference attendee asked how CO2emissions from FLNG compare to
CO2emissions from onshore LNG facilities. Mr. Pek noted that FLNG
vessels will have the capability to remove CO2 from
field gas and reinject it into reservoirs, although this option
was not utilized for Prelude. However, Mr. Pek noted that the
combined-heat-and-power-generation technology used for Prelude,
along with the cooling water obtained from great sea depths,
helps eliminate CO2emissions, making the FLNG design as
carbon-efficient as that of an
onshore LNG facility.

Another audience member asked how maintenance shutdowns, which are
extensive and time-consuming for onshore LNG plants, would be
implemented on Prelude and other FLNG projects. Mr. Pek noted that
continual maintenance would be carried out at Prelude during
normal operations, unlike onshore LNG terminals, which normally
shut down for maintenance. Prelude will house 110 workers
during normal operations and will have the capacity to
accommodate 150 people during maintenance periods.

Statoils Hammerfest inspires future FLNG. The
next speaker, Dr. Jostein Pettersen, LNG technology advisor for
Statoil ASA, spoke about technical and operational innovations
for onshore LNG and FLNG. Dr. Pettersen briefly discussed the
development of the Snøhvit gas field in the 1980s and
the construction of the Hammerfest LNG
plant, which he called A pioneering development for
Statoil, and certainly a challenging one in a lot of
ways, due to the harsh cold and darkness conditions in
the Arctic climate of northern Norway.

Dr. Pettersen acknowledged that an FLNG vessel was
originally considered for the Snøhvit field development,
although an onshore LNG plant was ultimately chosen. The
process facilities for the Hammerfest plant were built on a
floating barge, which served as a predecessor for FLNG. The construction included a compact and
modularized layout and prefabricated facilities, just as in FLNG
design.

Statoils FLNG design concept, which has been under
development since 1985 and for which feasibility, concept and
pre-FEED studies have been completed, includes a double
mixed-refrigerant (DMR) liquefaction process with mechanical
compressor drivers and the option for side-by-side or tandem
offloading. Lastly, Dr. Pettersen outlined three major areas of
FLNG work on which Statoil is focusing:

--- Acid gas removal (to prevent freeze-out in the
liquefaction process)
--- Offloading system selection
--- The large amounts of cooling water needed for
operation.

Liquefaction technology selection for
FLNG. Air Products and Chemicals Inc.s Lead
Process Engineer, Dr. Justin Bukowski, spoke about the
selection of a liquefaction process for FLNG, which he called
a very basic and important choice to
make when designing an LNG facility and also the
heart of the LNG facility.

Dr. Bukowski outlined several criteria for evaluating
liquefaction processes for FLNG, including efficiency (i.e.,
LNG production capacity divided by the refrigeration power
needed); train capacity (how much LNG can be produced at a
single train); and equipment count (heat exchangers,
precoolers, etc.). Dr. Bukowski pointed to weight, size and
layout limits as important considerations. Wave- and
wind-induced vessel motions dictate the mechanical strength
requirements and the effects on two-phase flow in
equipment.

Also, flammable inventory, such as propane tanks, may
attract concerns from FLNG operators because it is difficult to
separate living quarters from process areas. Corrosive marine
environments pose additional
challenges to successful, long-term FLNG operation.

To meet challenges, Dr. Bukowski offered several solutions,
including robust equipment design and the appropriate selection
of refrigeration technology. The process engineer recommended
using coil wound heat exchangers (CWHEs) for safety and reliability, as they are proven to
resist high thermal stresses. Also, the dual containment of
leaks is achieved with tubes being located inside of the shell,
which results in less downtime and more availability, as LNG
operations can continue until maintenance can be performed to fix
non-critical leaks.

Dr. Bukowski next outlined the pros and cons of four
possible liquefaction processes for FLNG: DMR, single
mixed-refrigerant (SMR), nitrogen (N2) recycle and
precooled N2 recycle. Pre-cooled MR, such as the
C3MR (propane-cooled) process, has the highest efficiency and a
large capacity (5 MMtpy or more of LNG output), although the
propane kettles needed for this process leave a large
footprint. DMR, on the other hand, uses a second MR for
precooling, and has the same efficiency and capacity as C3MR.
However, with DMR, the propane inventory can be minimized at a
small cost. For these processes, proper design of the CWHEs
mitigates the effects of motion on two-phase flows.

The SMR process achieves precooling and liquefaction with
the same refrigerant in a single exchanger. LNG production of 1
MMtpy2 MMtpy can be achieved at a single train, which is
around 87% of the C3MR/DMR process efficiency. Like C3MR and
DMR, motion problems are eliminated with proper CWHE
design.

Thirdly, the N2 recycle process is characterized
by multiple turboexpanders, an all-vapor refrigerant, no motion
sensitivity, higher flow rates and larger piping. LNG
production is pegged at 1.5 MMtpy for a single train, or 75% of
the C3MR/DMR process efficiency.

Lastly, precooled N2 recycle does not use a
hydrocarbon refrigerant and can achieve
LNG production of 2 MMtpy in a single train, or around 85% of
the C3MR/DMR process efficiency. Motion is mitigated for both
N2 recycle technologies with proper CWHE design.

In summary, Dr. Bukowski noted that all of the processes
have advantages and disadvantages. There are many
processes, and they are all suitable for FLNG, and [the process
choice] really depends on what [the customer] values for
the technology selection for the
project, he said. Dr. Bukowski also explained that natural gas
liquids (NGL) extraction in these processes can take place
upstream, or it can be integrated downstream in the precooling
scrub column.

Design methods for FLNG safety engineering. The last
speaker on the panel, Technip risk assessment and
quantification expert, Jérôme Hocquet, spoke to
attendees about the safety studies undertaken for FLNG
projects. Since FLNG is a new kind of facility, Mr.
Hocquet said, it comes with new safety issues.

An FLNG vessel, which condenses the processes and equipment
needed for an entire onshore LNG plant into one sixth of the
space, is essentially a congested environment, Mr. Hocquet said.
Therefore, the proximity of gas processing
units to living quarters is a concern, as are the potential for
gas leaks and explosions, the possible release of cryogenic
material, and the potential for steel embrittlement.

Safety studies undertaken for FLNG facilities examine proper input
to the design in the case of hazardous events, which ensures
that personnel will be able to escape safely in the case of a
major accident. Inherent safety principles, such as hazard
prevention to reduce the likelihood of loss of containment and
ignition, are also examined. Suitable fire protection,
separation distances between personnel and equipment, and
passive cryogenic protection for critical structures and
equipment are other important components of such safety
studies.

Mr. Hocquet concluded that a performance-based approach is
the only proper approach for the safety engineering of FLNG to
date, and it will remain the base until specific codes and
standards are developed for the safety design of FLNGs. Over
the last five years, Technip has completed several FLNG project studies and developed
risk-based study methods to make FLNG vessels both safe and
economically feasible.

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